Conventionally known are erasing apparatuses which are capable of erasing an image having been formed on a sheet in an erasable color material. The erasable color material employed can be, for example, heated and thereby decolorized. The erasing apparatus is capable, for example, of heating the sheet on which an image has been formed with the aforementioned erasable color material, thereby erasing the image. A number of times of repeated erasures on the same sheet may possibly cause the sheet to deteriorate. The erasing apparatus is thus required of a technique for recording the erase count on the sheet as a history.
Meanwhile, some erasing apparatuses are adapted to read the image before being erased, thereby restoring the image after the erasure of the image. Some other erasing apparatuses are designed to erase the image and then read the remaining image so as to determine whether the sheet is reusable on the basis of the level of the residual of the image. These erasing apparatuses are required to have a reading section disposed on both upstream and downstream stages of the erasing section in order to restore the image or determine the reusability of the sheet after the erasure of the image. This leads to an increase in costs.
Thus, there is a need to develop a technique for addressing these problems at the same time, that is, the technique for recording the erase count on the sheet as a history and achieving at low costs the restoration of the image as well as the determination of the reusability after the erasure of the image.